How Can A White Supremacist Be 14 Percent Sub-Saharan African?

Craig Cobb, an outspoken white supremacist, made national news a few months ago when he announced a plan to turn the tiny, remote town of Leith, N.D. — population: 19 — into a haven for white supremacists.

To advance his cause, he thought it wise to go on a daytime talk program, The Trisha Goddard Show (recent topics: "Test Me! I Never Sold My Daughter For Drugs" and "Family Race War: I'm Devastated My Daughters Are Dating Black Men"), and agree to a genetic test to prove his racial purity.

As you probably guessed, he was trolling the Fates.

The test determined that 14 percent of Cobb's DNA came from sub-Saharan Africa, according to Goddard, the show's host.

"Oil and water don't mix," Cobb protested. He later said that the results were part of a plot by the show to "promote multiculturalism."

So yes — justice is poetic and all that. But we had another reaction: Just what does being "14 percent sub-Saharan African" even mean? We often talk about race being a social construct and not a biological fact, so how much can science tell us about someone's race in cases like these?

Neil Risch, the director of the Institute for Human Genetics at the University of California, San Francisco, said that depending on how thorough a DNA test is, you can get a pretty accurate picture of where someone's forebears hailed from. "With genetic markers, you can actually do pretty well localizing people, even within a continent," Risch said. "You could pretty well separate Vietnamese, Chinese, Koreans."

The U.S. has a long history of conflating race with ethnic ancestry. Back in 1916, the eugenicist Madison Grant sketched out a crude framework for determining people's races:

"Whether we like to admit it or not, the result of the mixture of two races, in the long run, gives us a race reverting to the more ancient, generalized and lower type. The cross between a white man and an Indian is an Indian; the cross between a white man and a Negro is a Negro; the cross between a white man and a Hindu is a Hindu; and the cross between any of the three European races and a Jew is a Jew."

Similar logic informed the "one-drop" rule used in the Jim Crow era to determine for legal purposes whether someone was a Negro (the threshold for being classified as a Negro varied from state to state). Much of this, in reality, was just folks looking at someone else and guessing: Did that person seem like he might be black?

The racial categories still with us today aren't especially nuanced, either. Risch says there are averages of genetic profiles of people from certain populations, but even those aren't very illuminating for individuals. "I could tell you what the average Mexican would be — 50 percent European, 45 percent Native American and 5 percent African, but it's a very broad spread," he said. That makeup might vary wildly from person to person. The "typical" ethnic ancestry for a Mexican is very different from that of someone who is Dominican — or, say, a Filipino person whose DNA comes mostly from East Asia — but all might be lumped under the same racial umbrella and deemed to look "Latino."

The racial profiles we assign ourselves — I'm black, I'm Asian, I'm white — remain overly simplistic, even though we're better able to get these high-def pictures of our ancestries. As those pictures become cheaper, more accurate and easier to obtain, there are likely to be some big surprises in store for many of us. Like an ardent white supremacist who discovers that he's part sub-Saharan African.